Winemaker Tom Barry says these Assyrtiko grapes were burnt a bit, but dealt pretty well with the drought.

ABC Rural: Lucas Forbes

Some of South Australia's wine grape growers have seen their yields halve, as hot, dry conditions take their toll on some of the state's wine regions.

key points wine grape yields down

Key points:

Growers and winemakers say they haven't seen hot, dry conditions like this since 1982

At one winery in Port Lincoln, 50 per cent of the crop was lost in a matter of hours on one 48-degree day in January

Despite the low yields, most growers say what's left is of the highest quality they could ask for

However, many grape growers have reported being happy with the quality of the wines in spite of, or perhaps even because of, the tough conditions.

Clare Valley Wine and Grape Association executive officer Tania Matz said fans of Clare Valley wines should put in orders as soon as possible to avoid missing out, because there would not be much around.

Clare Valley Wine and Grape Association executive officer Tania Matz says fans of the region should be putting orders in soon so as not to miss out.

"We were given plenty of warning that it was going to be full-on. I think Port Augusta broke the state record that day and we got to 48 degrees here in Port Lincoln," he said.

"We watered and we put on some sun protection and we had the bottom of the vines all fluffy and not radiating it back up as much as it could.

"But by one o'clock we knew we were in big trouble."

Mr Ford said the riesling was the hardest hit.

"That had quite a bit of liquid in it at that stage and wasn't far off from being picked and we probably lost a good 60 per cent of that, which is heartbreaking — especially for my brothers who do the most work on the vineyard," he said.

"The sauvignon blanc handled it a little bit better and we maybe lost 20 per cent of that.

"And the reds, that didn't have a very good flowering to start with, were three or four weeks behind with moisture in the berries, so they handled it quite well," Mr Ford said.

Quality on the way

Mr Ford said, despite the low yields, the grapes that were picked were of the highest quality he could ask for.

He said it was because there were not as many grapes left on the vines.

"Some wineries might ask vineyards to drop fruit up to six weeks out, so they actually will cut off perfectly good grapes just so the vine concentrates and really puts the effort into the remaining grapes," he said.

"So in effect, because it was sort of a month before we picked, those berries dried off and died and so the same principle applies.

"This is exactly what happened in 2014 when we won the Wine State Riesling of the Year, it was the ugliest fruit we have ever picked, but we are not in a photography competition, we are after the juice and that is what the winemaker can work with.

"So there won't be a lot of wine, but we are positive it will be top quality."

Peter Teakle Wines in Port Lincoln was not affected as much by the heat because their location provides plenty of shade.